‘Prefer not to say’ - option in feedback questions,

No matter what I've bought, or if it's a job interview form, etc. I refuse point-blank to answer such personal questions.

If the item or job has something to do with my religion/lack of, or skin colour, then obviously I would answer, but not for any other reason.

I'm 60 now, never married/no kids by choice, and am an Athiest, but when I was 40 and went for a job interview, I didn't fill in the religious/ethnic things.

I got the interview, and he asked me my marital status and religion, so I said it has nothing to do with the job description. He kept pushing, so I just walked out!

And I won't fill them in for shopping items either!

I can only speak for myself but I really would not like to write 'None of your business' to any question in a feedback questionnaire I was filling in voluntarily.

I thought any personal information had to be kept to a minimum these days.
Yes, I would most certainly tick a 'None of your Business' option for unnecessary questions.